The invention relates to an illumination device for a motor vehicle including a light source constructed of a number of semiconductor diodes as well as a scanner onto which a light beam generated by light of the light source falls and which changes the position of the light beam during the operation of the illumination device and thereby moves a light spot generated by the light beam at a distance from the illumination device. A predetermined light distribution is generated by the moved light spot.
Scanning illumination systems for motor vehicles are known from the prior art, which systems use a scanner to deflect a light beam generated by means of at least one semiconductor diode to creating various light distributions.
The publication WO 2010/058323 A1 discloses a scanning illumination device for a motor vehicle, wherein monochromatic laser light falls onto a scanner with which the light distribution is generated. Located behind the scanner is a conversion element in the form of a phosphor plate with which white light is generated from the laser light. For delimiting the light distribution in the distant field, an aperture is positioned on the phosphor plate. By way of this aperture a light-dark boundary can be generated in the light distribution, which however cannot be varied.
The invention seeks to solve the problem of creating a scanning illumination device for a motor vehicle by means of which a predetermined light distribution can be generated simply and efficiently.
This problem is solved by an illumination device, according to the invention, for a motor vehicle. The illumination device includes a light source constructed of a number of semiconductor diodes as well as a scanner onto which a light beam generated by light of the light source falls and which changes the position of the light beam during the operation of the illumination device and thereby moves a light spot generated by the light beam at a distance from the illumination device. A predetermined light distribution is generated by the moved light spot. A beam-delimiting device is provided between the light source and scanner by which the cross section of the light beam is delimited along a predetermined boundary. The illumination device is designed such that one or more light-dark boundaries are formed in the predetermined light distribution by at least one segment of the predetermined boundary.
The illumination device according to the invention includes the light source constructed of a number of semiconductor diodes as well as a scanner onto which a light beam generated by the light of the light source falls and which changes the position of the light beam during operation of the illumination device and thereby moves a light spot generated by the light beam at a distance from the illumination device and, particularly, in the distant field of the illumination device. This moved light spot is used to generate a predetermined light distribution. Appropriately activating the scanner generally allows different light distributions to be generated according to application. The term “distant field” describes the light distribution at a distance from the illumination device that is significantly larger than the dimensions of the illumination device, located in particular within the range of 25 m in front of the illumination device. The term “light beam” describes a light beam consisting of light rays delimited in angle or space, where the light rays in the beam can run essentially parallel as well as diverge from or converge with one another.
The illumination device according to the invention is characterized in that positioned between light source and scanner is a beam-delimiting device with which the cross section of the light beam is delimited along a predetermined boundary. The illumination device is designed such that with at least one segment of the predetermined boundary one or more light-dark boundaries are formed in the predetermined light distribution. In other words, through the predetermined boundary that is formed in the light spot generated by the light beam, a light-dark boundary is generated in the light distribution through appropriate activation of the scanner. The predetermined boundary moves together with the light spot and facilitates in a simple manner the flexible formation of complex contrast structures in the light distribution.
The illumination device according to the invention preferably contains a laser light source. In other words, the semiconductor diodes are comprised of one or more laser diodes. In particular, the laser light source is comprised exclusively of laser diodes. The laser diodes preferably feature a maximum output of at least 1 W and, in particular, between 1.5 and 5 W.
In an especially preferred embodiment, the predetermined boundary, according to which the cross section of the light beam is delimited, includes one or more straight lines with which the light-dark boundary or the light-dark boundaries in the predetermined light distribution are formed. In a preferred variant, the predetermined boundary is a parallelogram, for example a rectangle. Guided by the directions of the edges of the parallelogram, a light-dark boundary can be generated by moving the scanner accordingly, as in the case of, for example, the low-beam characteristics of an illumination device designed as a headlight and explained below with reference to FIG. 2.
In an especially preferred embodiment, the apparatus features an aperture for beam delimitation, with the aperture opening delimiting the cross section of the light beam along the predetermined boundary. If necessary, the aperture opening can be variable to allow the predetermined boundary to be modified. The device for beam delimitation can, if necessary, be generally designed such that the predetermined boundary can be varied.
In an especially preferred embodiment, the aperture is arranged within an optical device that aims or focusses the light beam on the aperture opening and projects the light beam directed at the aperture onto the scanner. In a preferred variant, this optical device comprises at least a lens and/or at least a reflector in front of and/or at least a lens and/or at least a reflector behind the aperture.
As an alternative to or in addition to an aperture, the beam-delimiting device can also include a light conductor and, in particular, an optical fiber in which the light of the light source is conducted. In this case, the cross section of the optical fiber determines the appropriate delimitation of the light beam.
In another preferred embodiment of the invention, the light source generates monochromatic light, with a conversion element being provided for converting the light of the light source into white light. Conversion elements of this type are known from the prior art. For example, if blue/violet laser diodes having an emission wavelength of 450 nm/405 nm are present, a phosphor conversion element made of nitride phosphor, oxide nitride phosphor or cerium-doped YAG phosphor can be used to generate white light.
The conversion element, which is designed in particular as a film, can be arranged at different positions in the illumination device depending on the design of the invention, e.g. at a position before or after the light beam passes through the scanner. In an especially preferred embodiment, the conversion element is provided between the light source and scanner and, in particular, on the beam-delimiting device. If the beam-delimiting device comprises an aperture, the conversion element is preferably arranged in the aperture opening.
In another variant of the illumination device according to the invention, an exit optic is provided onto which the light beam falls after passing the scanner and which generates the light spot.
According to an advantageous design of the invention, the illumination device is designed such that the scanning speed at which the light spot is moved, the scanning path along with the light spot is moved, and/or the size of the light spot can be varied and can be controlled for generating the predetermined light distribution. The scanning path corresponds to the movement pattern of the light spot, which is generated by changing the location of the light beam. By appropriately defining the scan path, the area in which a predetermined light distribution is present can be delimited. Moreover, the luminosity in these areas can be increased accordingly through multiple delineations of the same areas according to the defined scanning path.
In a preferred design of the embodiment just described, the scanner is a vector scanner with which the scanning speed and/or the scanning path and, in particular, both the speed and the path, can be varied. In another embodiment of the invention in which a set of exit optics is provided, the size of the light spot can be varied by means of this set of exit optics. In this case the set of exit optics preferably contains a lens and/or a reflector with a variable focal distance. Optical elements of this kind are known per se and are comprised of, for example, electroactive substances that change their characteristics when electrical current is applied in such a way to vary the focal distance of the lens or the reflector.
Depending on the application, the inventive illumination device can adopt various functions. In one embodiment, the illumination device comprises a headlight. A headlight is characterized in that it actively illuminates the vicinity around the vehicle. If necessary, the illumination device according to the invention can comprise a signal light that is characterized in that it functions solely for signaling to other traffic.
In a preferred variant, the illumination device is realized as a headlight such that low-beam characteristics are generated as a predetermined light distribution during operation. This is characterized by a sharp light-dark line, which, according to the invention, can be generated by the beam-delimiting device in a simple manner. If necessary, the illumination device can also be designed such that it generates high-beam characteristics as a predetermined light distribution during operation.
In addition to the inventive illumination device, the invention also relates to a motor vehicle comprising one or more of the inventive illumination devices.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.